University of California, Merced

Matt Wedel

Howdy, Matt Wedel here. This is the Sauropod Vertebra Picture of the
*Week* (or SV-POW! as we like to call it), and you just got a post
yesterday, so what are we doing back here already? Mike and Darren and I
are trying to get SV-POW! up and running as quickly and smoothly as
possible, and the best way to do that is to post. And as long as we're
posting, we might as well get a little work done, too.

(Also, we will follow our titular guideline and post *at least* one
sauropod vertebra picture every week; however, we reserve the right to
bring you even more doses of awesome than you expected.)

[](http://svpow.files.wordpress.com/2007/10/basic-vertebral-anatomy.jpg "basic-vertebral-anatomy.jpg")

[![basic-vertebral-anatomy.jpg](https://svpow.files.wordpress.com/2007/10/basic-vertebral-anatomy.jpg?w=500&h=341){align="left"
height="341"
width="500"}](http://svpow.files.wordpress.com/2007/10/basic-vertebral-anatomy.jpg "basic-vertebral-anatomy.jpg")

Today we're covering the very basics of vertebrae. You've been toting
around a full set for your entire life, but just in case you've never
gotten acquainted, here's the skinny.

**Vertebrae** are the segments of bone or cartilage that make up the
spinal column or backbone. In sharks and rays the vertebrae are composed
of cartilage, but in almost all of the bony fish and their
descendants--including you--the vertebrae are made of bone.

In most fishes and amphibians there is little or no **regional
specialization** of the vertebral column, but in more derived tetrapods
(vertebrate animals with four limbs, or whose ancestors had four limbs)
the vertebral column can be divided into at least four regions:

**Cervical vertebrae** are neck vertebrae. They usually have fixed
(non-mobile) ribs on either side. You may not know it, but your own
cervical vertebrae have these ribs. They're just very short. In some
sauropods the cervical ribs were mind-bogglingly long, up to 4 meters or
more in length, but that's a story for another post. With a couple of
weird exceptions, all mammals have only 7 cervical vertebrae, even the
giraffe. But other clades are not so limited. For example, birds can
have 24 or more. The largest number of cervical vertebrae in any known
sauropod is 19.

**Dorsal vertebrae** are the vertebrae that fall between the neck and
the sacrum. In sauropods they always have large, mobile ribs, of the
sort that you usually think of when you hear the word 'rib'. In mammals
the dorsal series is divided into thoracic vertebrae, which have ribs,
and lumbar vertebrae, which do not, but in sauropods all of the dorsal
vertebrae have ribs. Sauropods had as many as 12 or 13 dorsal vertebrae
and as few as 9.\*

Behind the ribcage is the **sacrum**, a block of fused sacral vertebrae.
The sacrum articulates with the bones of the pelvis; this is the only
bony attachment between the appendicular skeleton (limbs and limb
girdles) and the axial skeleton (skull, vertebrae, and ribs). There is
no bony connection between the shoulder girdles and the vertebral
column. Instead, the shoulder girdles and forelimbs are bound to the
body by ligaments and muscles. Sauropods had between 4 and 6 sacral
vertebrae.\*

**Caudal vertebrae** are tail vertebrae. There is usually more change
along the caudal series than in other regions of the vertebral column.
The vertebrae closest to the sacrum often closely resemble unfused
sacral vertebrae, but down at the end of the tail the vertebrae are
usually reduced to simple rods or nubs of bone. Your coccyx or tailbone
is made of fused caudal vertebrae, so technically you do have a tail
skeleton, just not an external tail (unless you're lucky).

Well, that's quite enough for now. We'll take up the parts of a vertebra
in a future post. And it won't all be anatomical drudgery; we wouldn't
have created SV-POW! if we didn't have really cool stuff to show off.

The skeleton in the image above is that of *Brachiosaurus*. The cervical
vertebra, BYU 12867, is also from *Brachiosaurus*, and it is 94 cm long.
The dorsal vertebra, OMNH 1382, is from *Apatosaurus*, and it is 93 cm
tall (however, the top of the neural spine is missing so it would have
been more than a meter tall in life).

\* Some sauropods might have more dorsal vertebrae or fewer sacral
vertebrae, depending on the definition of 'sauropod' that one uses.
Right now it seems that at least some of the animals traditionally
called prosauropods are, in fact, primitive sauropods.


Howdy, Matt Wedel here. This is the Sauropod Vertebra Picture of the
<em>
 Week
</em>
(or SV-POW! as we like to call it), and you just got a post yesterday, so what are we doing back here already? Mike and Darren and I are trying to get SV-POW! up and running as quickly and smoothly as possible, and the best way to do that is to post. And as long as we’re posting, we might as well get a little work done, too.

Messages de Rogue Scholar

Tutorial 1: Regions of the vertebral column